Shared/class;local/instance

[Gregor.pa@Xerox.COM]

    Date: 09 Oct 87 15:39 PDT
    From: Dick Gabriel <RPG@SAIL.Stanford.EDU>


    Danny and I agreed to the following terminological definition. If y'all
    agree, we'll go with it:

This all seems fine except...

    2. We state that a slot with allocation type :instance is a local slot
    and a slot with allocation type :class is a shared slot, and that
    we leave room for extensions to CLOS in which other allocation types
    are possible, but stipulate that only extensions that produce shared
    or local slots are allowed.

I don't understand this.  What does this restriction mean?  Why?
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